How to get list of all images in a scene with python
If you just want to iterate over the images:

import bpy

for img in bpy.data.images:
    print("name=%s, filepath=%s" % (img.name, img.filepath))


Note this could contain 'render result' and materials which you might want to filter.
See the docs to see what attributes could be interesting like 'file_format', 'filepath', 'filepath_from_user', 'filepath_raw'...